A window through the walls of our classroom. This is an interactive learning ecology for students and parents in my Pre-Cal Math 20S class. This ongoing dialogue is as rich as YOU make it. Visit often and post your comments freely.

Friday, November 21, 2008

Friday, November 21st, 2008

Today Mr. K first off talked about the blog, telling us how to write label's properly because if you don't, then you won't get the mark's that you deserved for it. Then he moved on mentioning to us that since we were having difficulty with vocabulary, he now will add onto the blog something that will help us out. This is a site found in the right hand side of the blog with a link called "wordequationswiki" sort of like wikipedia, only this time we could add on word's that we don't understand, ourselves to this site.

Our next unit that we began since we had to move on, is called Geometry. For this unit we need to know volume of a cylinder and sphere formula's. There is also another one that we also need to know about, and it is called the baseball theorem. For example, if you take a baseball and cut all the stitches, and then unfold it, it would have 4 circles. And these 4 cirlcles is what is used to find out the surface of a sphere. This is because if you take the 4 circles multiply it by pie and also multiply the radius by itself 2 times, then you would get the surface of a sphere. Note when multiplying with pie you can't just multiply it with just "3.14". You can't just do that you have to use the whole thing because if you were to use "3.14" that'll only be close to pie unlike if you use the whole thing "3.141592654" your answers will be fully correct.

To get us started with Geometry Mr. K gave us an example:

EX) A sphere fits exactly inside a cylinder. Find the volume of each of the size's of cylinder's with spheres inside them. Is there a relationship or a pattern?

First off you have to find the height of the cylinder. You get the height of the cylinder by the diameter of the sphere. And then once that is settled, for all the 3 size's you plug in the measurement's in the formula. For the volume of cylinder formula this is what it would be like : . For the volume of sphere formula itwould look like this :

Let's start off with the smaller size first to get you help started and to show you how to do it for the other sizes .

First find the volume of the cylinder:

VCYL =

=

== 50.2654

Then find the volume of the sphere inside :

VSPH ==== 33.5103

VCYL == 50.26

VSPH == 33.51

Now do the same method for the medium and the large sizes, which will give us:

Medium Sized:

VCYL =

VSPH =

Large Sized:

VCYL =

VSPH =

In conclusion, using the medium size one, one and a half spheres fit in each cylinders :

===

Our assignment for today was Excercise 23, Questions: All. A reminder on Monday, November 24th 2008, is our test on Radicals and Exponents, so study hard.